Fig. 5

Autophagic and UPR inhibition in p53 mutant cells. a Immunoblot analysis of the indicated proteins in HCT116 transfected with non-silencing control siRNA (Ctr) or siRNAs targeting Atg5 (siAtg5) or BiP (siBiP) for 72 h with or without amino acid starvation (HBSS medium, Stv) for 24 h. b The growth curve of HCT116 cells transfected with non-silencing control siRNAs or siRNAs targeting Atg5 or BiP or Atg5 plus BiP (co-transfection), determined using a cell counting kit. c The number of apoptotic HCT116 cells transfected with non-silencing control siRNAs or siRNAs targeting Atg5 or BiP or Atg5 plus BiP (co-transfection), determined using a FACS analyzer. Data shown are means ± SEM (n = 3). *; p < 0.05 by Dunnett’s multiple comparison test. d Immunoblot analysis of Atg5, BiP, PARP, and cleaved PARP in the indicated colon cancer cell lines transfected with non-silencing control siRNAs or siRNAs targeting Atg5 or BiP or Atg5 plus BiP (co-transfection). Actin was used as an internal control. e The number of apoptotic cells in the indicated cell lines transfected with non-silencing control siRNAs or siRNAs targeting Atg5 or BiP or Atg5 plus BiP (co-transfection), determined using a FACS analyzer. The status of p53 in each cell line is shown. Data shown are means ± SEM (n = 3). *; p < 0.05 by Dunnett’s multiple comparison test. f Summary of the effect of autophagic inhibition on colon cancer. Atg5 deletion causes DNA damage and ER stress. DNA damage leads to CHK1-p53 axis activation. ER stress up-regulates BiP and eIF2α activation, and BiP inhibits eIF2α activation. Finally, apoptosis induced by caspase 3 and CHOP exerts an anti-colorectal cancer effect